There's a glass half full of water.
https://gyazo.com/6740e7576c92a3cdca804b2e6c5227a3
Where did this even if story first appear? According to Quote Investigator it is unknown who was the first, as the earliest one found is anonymous Quote Investigator: The earliest match found by QI appeared in “The Evening Sun” of Baltimore, Maryland in April 1929. The statement occurred in a filler item without attribution. Boldface added to excerpts by QI:
If he says his gas tank is half-full he’s an optimist. If he says it’s half-empty he’s a pessimist.
(DeepL) If he says he has half a tank of gas, he is an optimist. If he says it is only half full, he is a pessimist.
A metaphor that is easy to visualize
But the cup dictates 100%.
The result implicitly leads to a decision that "it is better to aim for 100%" (better to fill the glass with water)
Sometimes used in the sense of [know one has enough
relevance
This metaphor evolved
However, the level of abstraction has increased.
6. Changes in Perception
“The glass is half full” and “The glass is half empty” are descriptions of the same phenomenon but have vastly different meanings. Changing a manager’s perception of a glass from half full to half empty opens up big innovation opportunities.
(DeepL) Changing a manager's perception from a glass half full to a glass half empty creates an opportunity for great innovation.
I say it would be more beneficial to recognize that this is "half empty."
---
This page is auto-translated from /nishio/コップに半分水がある using DeepL. If you looks something interesting but the auto-translated English is not good enough to understand it, feel free to let me know at @nishio_en. I'm very happy to spread my thought to non-Japanese readers.